Atomic Emission Spectrometry of Microsamples in a Glow Discharge

A glow discharge system for atomic emission spectrometry is evaluated for physical and analytical characteristics. Lead (as the nitrate) is the model element used for these studies. The sputtering characteristics of several electrode designs are studied with the best system tried resulting in total sample vaporization in less than 1 s. Discharge currents up to 200 mA at a discharge voltage of 1200 V and a pressure of 2 torr are found to give the best results. The detection limit for lead is 0.9 ng and the linear dynamic range of response is greater than 2 orders of magnitude. Sodium chloride at a 100-fold excess amount causes a 50% decrease in the signal level.